Journal of Postgraduate Gynecology & Obstetrics is an Open Access, peer reviewed online journal published by Department of Obstetrics and Gynecology of Seth G. S. Medical College and K.E.M. Hospital, Parel, Mumbai, 400012, India.

Cesarean scar pregnancy is an infrequent condition whose incidence is steadily increasing due to liberal use of cesarean section in modern obstetrics. A high index of suspicion is needed in cases of previous uterine scar with implantation in and around the internal os. We report a case of scar ectopic pregnancy following previous 2 lower segment cesarean sections (LSCS) with completed family. She was treated with evacuation followed by scar excision and it was accompanied by tubal ligation. We intend to highlight the utility of a term ‘Low Lying Implantation of Ectopic Pregnancy’ (LLIEP) to cover all forms of ectopic pregnancies implanted in and around the internal os as it reduces diagnostic confusion.

Introduction

Ectopic pregnancy in and around internal os could be cervical pregnancy (CP), cesarean scar pregnancy (CSP), and cervico-isthmic pregnancy (CIP) which does not fit in either of the first two. Cesarean scar pregnancy is an ectopic pregnancy implanted in the myometrium of previous cesarean scar.[1] The overall increase in the number of cesarean sections over the past 2 decades along with improved detection of these pregnancies due to high resolution transvaginal ultrasonography have resulted in increased incidence of scar ectopic in recent times.

Case Report

A 26 year old, G3P2L2, with 8 weeks of gestation and sonologically corresponding to 6 weeks with previous 2 LSCS presented at a tertiary referral center with vaginal spotting for 8-10 days. There was a single episode of heavy vaginal bleeding associated with passage of clots. There was no hematuria. Her ultrasound (USG) showed gestational sac in myometrium of anterior uterine wall at the site of LSCS, suggestive of scar pregnancy. MRI confirmed 4.5x4 cm mass in the anterior wall of isthmic area with no invasion of the bladder. The fundus was empty and the cervico-isthmic myometrium was extremely thin. Her β HCG was 78,000 mIU /ml. The patient was hemodynamically stable. The patient and her family were counseled about the therapeutic options in presence of high β HCG titres and extremely thin isthmic wall. They opted for minilaparotomy with evacuation of products and tubal ligation. Intraoperatively, a 3x3 cm gestational sac was observed in the lower uterine segment below the level of previous scar and the internal os. Incision was taken at the scar site and products were evacuated. Defect was sutured with Polyglactin 910. Uterine cavity was also curetted to remove any products in case they were adhered to uterus below the lower uterine segment. The material sent for histopathology confirmed the products of conception. There was minimal oozing from the implantation site. Foley’s catheter no.12 was placed in the cervical canal for tamponade after cutting its tip so that any blood from uterine cavity could drain out. Intraoperative blood loss was 250 cc. Incidentally, a para tubal cyst of 4x4 cm was diagnosed and removed which was confirmed on histopathology. Catheter was removed on postoperative day 3 as there was no bleeding. Her postoperative course was uneventful.

The most likely mode of occurrence of scar ectopic is the entry of the blastocyst in the scar myometrium through the microscopic dehiscent tract resulting from trauma due to previous cesarean sections, induced abortions and following curettage procedures.[2,3] IVF causes LLIEP without any history of preceding trauma, albeit rarely.[4] Jurkovic et al suggested that there is increased incidence of scar ectopic with increase in the number of cesarean sections probably due to increased surface area of the scar tissue.[5] It has been suggested that early placenta accreta (EPA) and placental implantation in CSP are histopathologically indistinguishable and may represent different stages in the disease progression, where CSP may later advance to morbidly adherent placenta.[6] Tsai et al have suggested the use of new term ‘Low Lying Implantation of Ectopic Pregnancy (LLIEP)’ to cover all types of aberrant ectopic implantations in the lower uterine segment in the first trimester.[7] It is understandable that the use of the term LLIEP during preoperative ultrasound would enable the clinician to simplify diagnosis, without the need to change the treatment policy. The trophoblastic invasion of the cervical pregnancy and the precise location below the internal os are cardinal criteria in diagnosis of cervical ectopic. Accurate diagnosis of CSP can be made by ultrasound in a sagittal position, which shows an empty uterine cavity and cervical canal.[8] Typically, to differentiate a CSP from a cervical pregnancy; in CSP, gestational sac and urinary bladder should be juxtaposed. In our case, the cervico-isthmic area was seen distended with the gestational sac.

Clinicians have managed LLIEPs’ in multiple ways. Uterine artery embolization, dilatation and curettage, systemic administration of methotrexate, ultrasound guided intralesional instillation of methotrexate and local excision of the mass include some of them. Treatment should be individualized according to the gestational age, fetal viability and the patient’s desire for future fertility. There are conflicting opinions about speedy action of methotrexate to stop embryonic growth.[9] Our patient had a fetus with cardiac activity and high β HCG levels. She had completed her family and was apprehensive about adverse effects of methotrexate and small chance of failure of treatment associated with it. As per her desire, tubal ligation was performed with the evacuation of the ectopic. We observed that implantation had occurred below the level of the uterine arteries in the cervical canal. On incising the lower uterine segment the products of conception did not seem densely attached to the myometrium of the scar tissue. An accurate ultrasound is vital in diagnosis of scar ectopic. Confusion with missed abortion can lead to inadvertent curettage, which might even lead to obstetric hemorrhage requiring obstetric hysterectomy. Therefore MRI may be done in hemodynamically stable patients to confirm the diagnosis.

Conclusion

Implantation in and around the site of cesarean scar could be catastrophic and life-threatening although it occurs infrequently. The incidence of LLIEP is going to increase due to increase in number of cesarean sections. Hence careful transvaginal ultrasonography in all women with previous scar with use of power Doppler could go a long way in avoiding misdiagnosis. The terminology of LLIEP helps to avoid the confusion about diagnosis of these overlapping conditions, which are similar not only in clinical characteristics and presentation but also in treatment and prognosis. Though there is no consensus on the best mode for the treatment of LLIEPs’, immediate termination of pregnancy is advisable. Senior obstetricians should be involved in counseling, decision making and management of such cases.